<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        * {
            margin: 0;
            padding: 0;
        }
        
        ul {
            list-style: none;
        }
        
        nav {
            width: 800px;
            height: 35px;
            margin: 100px auto;
        }
        
        nav ul li {
            width: 100px;
            height: 36px;
            float: left;
            /* border: 1px solid #000; */
            box-sizing: border-box;
            text-align: center;
            line-height: 36px;
            position: relative;
            perspective: 500px;
            transform-style: preserve-3d;
        }
        
        .top,
        .bottom {
            width: 100%;
            height: 100%;
            background: skyblue;
            position: absolute;
            transition: all 1s;
        }
        
        .top {
            transform: rotateX(-90deg) translateZ(17.5px) translateY(17.5px);
        }
        
        .bottom {
            background: palegoldenrod;
        }
        
        nav li:hover .bottom {
            transform: rotateX(90deg) translateZ(17.5px) translateY(-17.5px);
        }
        
        nav li:hover .top {
            transform: none;
        }
    </style>
</head>

<body>
    <nav>
        <ul>
            <li>
                <div class="top">我的导航</div>
                <div class="bottom">我的导航</div>

            </li>
            <li>
                <div class="top">我的导航</div>
                <div class="bottom">我的导航</div>

            </li>
            <li>
                <div class="top">我的导航</div>
                <div class="bottom">我的导航</div>

            </li>
            <li>
                <div class="top">我的导航</div>
                <div class="bottom">我的导航</div>

            </li>
            <li>
                <div class="top">我的导航</div>
                <div class="bottom">我的导航</div>

            </li>
            <li>
                <div class="top">我的导航</div>
                <div class="bottom">我的导航</div>

            </li>
            <li>
                <div class="top">我的导航</div>
                <div class="bottom">我的导航</div>

            </li>
            <li>
                <div class="top">我的导航</div>
                <div class="bottom">我的导航</div>

            </li>
        </ul>
    </nav>
</body>

</html>